Jenn & Chris Carter

Thank you both, I'll work on checking terminals and grounds. I forgot to mention that we did change the battery during this process but it makes sense that if the wiring/terminals are not right the problem would persist with a new battery. I'll be checking the tail lights for that issue as well.

Hey experts, I've got a 2015 Yukon XL Denali that's been having some quirky electrical events on occasion...various (unwarranted) warning messages on the dash display, and twice while at low speeds in a parking lot the car has had the dash lights flicker/blink and then the car died. Once on an interstate on ramp it seemed like every electrical component started going crazy and the car felt like it was stalling out for a few seconds before it all stopped as quickly as it started. I'm also experiencing the brake lights not working at times. I've had a few people wave me over to let me know that the right or left one is out, but it seems like they've never both been out at the same time. At first I only was aware of the right brake light intermittently not working and thought maybe it was the common issue of the wire breaking, I was about to pull the light and re-solder it when someone told me that the right was working and it was the left that was out. Since then we've realized that it is intermittent at best that either the right or left will be out for a time. My husband thinks that it's likely the alternator not keeping up with all the electrical draw that is making the different things act up. We got a voltage reader for the front cigarette lighter port and I've been keeping an eye on my voltage. It hovers between 13.8 and 14.7. Is there something else that we are overlooking that could be the culprit? I appreciate any input. Thanks.

thank you all for the advice. Thought I'd give an update. We could never find service records of fluid or filter changes for the transmission so we went ahead with a fluid exchange and new filter. Shuddering at 30mph was still present so we added the lube guard shudder fix. We never found specs on how much to add, so we used one at a time and drove for about 100 miles then added another tube until the shuddering stopped after 3 tubes. It's been smooth as silk since then.

thanks, I'll definitely look into reading codes first, I hadn't thought of that

Hi all, I'm new here and hoping y'all will be able to help give me some direction. I have a '15 Yukon XL Denali with the 6 speed MYC transmission and almost 140k miles, my transmission has begun shuddering when I'm driving between 25-35 miles an hour, does not seem to do this at really any other speeds. I spoke with a dealer who said their suggestion is just to go ahead and replace the transmission, this feels a little extreme at this point since Im not having hard shifts etc. I've owned the vehicle for the last year and put about 27k miles on it in a year. I have no records of any previous transmission maintenance and the fluid looked good when we purchased it. I know that dropping the pan is a pain in the neck, but I'm thinking that I need to change the filter since I have no idea how old it is. Husband is out of town and I'm wanting to get this dealt with ASAP. I'm pretty capable of doing a flush or dropping the pan if I have a good write up to follow, so any advice would be much appreciated. Also, what fluid have y'all had good luck with? Thanks, Jenn